CGAffineTransformMakeTranslation does not translate correctly - ios

Question

I see two different behaviors for CGAffineTransformMakeTranslation between simulator mode and the real device.
(on iOS 8.1)
For an iPhone4, to get CGAffineTransformMakeTranslation to work on the real device, I have to translate by twice the amount.
On the iPhone4s simulator, I have to translate just by the amount with not scaling.
Perhaps I'm missing something obvious but since both have the same number of logical pixels, I shouldn't have to adjust CGAffineTransformMakeTranslation to make translation work.
Here I have a view I'm pulling in and out of view by swiping:
CGRect menuOrigin = self.rootController.containerView.bounds;
switch (direction) {
case UISwipeGestureRecognizerDirectionLeft:
{
NSLog(#"Initial Position: %#", NSStringFromCGPoint(self.rootController.containerView.frame.origin));
NSLog(#"Initial Scale: %f", [self contentScaleFactor]);
NSLog(#"Initial Center: %#", NSStringFromCGPoint([self center]));
CGAffineTransform transform = CGAffineTransformMakeTranslation(-1.0 * widthToSlide, 0);
self.rootController.containerView.transform = transform;
[UIView animateWithDuration:0.4 animations:^{
self.rootController.containerView.transform = transform;
[self.rootController.containerView layoutIfNeeded];
} completion:^(BOOL finished) {
NSLog(#"Final Position: %#", NSStringFromCGPoint(self.rootController.containerView.frame.origin));
NSLog(#"Final Scale: %f", [self contentScaleFactor]);
NSLog(#"Final Center: %#", NSStringFromCGPoint([self center]));
}];
}
break;
case UISwipeGestureRecognizerDirectionRight:
{
CGAffineTransform transform = CGAffineTransformMakeTranslation(0, 0.0);
[UIView animateWithDuration:0.4 animations:^{
self.rootController.containerView.transform = transform;
[self.rootController.containerView layoutIfNeeded];
} completion:^(BOOL finished) {
}];
}
default:
break;
}
[self.rootController.containerView setNeedsDisplay];
[self setNeedsDisplay];
NSLog goes like this for the iPhone4 real device:
2015-10-15 01:12:37.547 Local[5307:60b] swipeLocalPull adjusting width 183
2015-10-15 01:12:37.556 Local[5307:60b] Screen size: {320, 480}
2015-10-15 01:12:37.559 Local[5307:60b] Initial Position: {0, 66}
2015-10-15 01:12:37.974 Local[5307:60b] Final Position: {-91.5, 66}
and for the iPhone4s iOS 8.1 simulator:
2015-10-15 01:19:19.479 Local[56380:3061577] swipeLocalPull adjusting width 183
2015-10-15 01:19:19.480 Local[56380:3061577] Screen size: {320, 480}
2015-10-15 01:19:19.480 Local[56380:3061577] Initial Position: {0, 66}
2015-10-15 01:19:19.886 Local[56380:3061577] Final Position: {-183, 66}
The simulator is translated correctly. Notice, the real device translated only half way to -91.5. Why is this and how can I detect or compensate for this. Sorry if this question has been asked before but I could not find the root cause for this behavior. I only care about x translation at this moment.
Anyone have clues for this behavior.?
Update
By request, here's a few extra outputs:
---iPhone4 values---
2015-10-15 17:20:59.591 Local[5617:60b] swipeLocalPull adjusting width 183
2015-10-15 17:20:59.596 Local[5617:60b] Screen size: {320, 480}
2015-10-15 17:20:59.599 Local[5617:60b] Initial Position: {0, 66}
2015-10-15 17:20:59.601 Local[5617:60b] Initial Scale: 2.000000
2015-10-15 17:20:59.603 Local[5617:60b] Initial Center: {201, 99}
2015-10-15 17:21:00.015 Local[5617:60b] Final Position: {-91.5, 66}
2015-10-15 17:21:00.018 Local[5617:60b] Final Scale: 2.000000
2015-10-15 17:21:00.037 Local[5617:60b] Final Center: {201, 99}
---iPhone4s Simulator---
2015-10-15 17:39:59.850 Local[57069:3104390] swipeLocalPull adjusting width 183
2015-10-15 17:39:59.851 Local[57069:3104390] Screen size: {320, 480}
2015-10-15 17:39:59.851 Local[57069:3104390] Initial Position: {0, 66}
2015-10-15 17:39:59.851 Local[57069:3104390] Initial Scale: 2.000000
2015-10-15 17:39:59.851 Local[57069:3104390] Initial Center: {201, 99}
2015-10-15 17:39:59.852 Local[57069:3104390] Final Position: {-183, 66}
2015-10-15 17:39:59.852 Local[57069:3104390] Final Scale: 2.000000
2015-10-15 17:39:59.852 Local[57069:3104390] Final Center: {201, 99}
They both seem to be at #2x scale so I expect the same code to work for both.
Working Code
I got it to work with the following(if someone explains why, then I'll just mark that as the answer):
switch (direction) {
case UISwipeGestureRecognizerDirectionLeft:
{
NSLog(#"Initial Position: %#", NSStringFromCGPoint(self.rootController.containerView.frame.origin));
NSLog(#"Initial Scale: %f", [self contentScaleFactor]);
NSLog(#"Initial Center: %#", NSStringFromCGPoint([self center]));
CGPoint currentPos = self.rootController.containerView.center;
currentPos.x -= widthToSlide;
[UIView animateWithDuration: .4
delay: 0
options: (UIViewAnimationOptionCurveLinear | UIViewAnimationOptionAllowUserInteraction)
animations:^{
self.rootController.containerView.center = currentPos;
}
completion:^(BOOL finished) { }
];
}
break;
case UISwipeGestureRecognizerDirectionRight:
{
CGPoint currentPos = self.rootController.containerView.center;
currentPos.x += widthToSlide;
[UIView animateWithDuration: .4
delay: 0
options: (UIViewAnimationOptionCurveLinear | UIViewAnimationOptionAllowUserInteraction)
animations:^{
self.rootController.containerView.center = currentPos;
}
completion:^(BOOL finished) { }
];
}
default:
break;
}
[self.rootController.containerView setNeedsDisplay];
[self setNeedsDisplay];